M2M is not about human population. 50 billion connections is still only around ten connections per cellular phone user. Think how many you already have - I've done a quick audit around my home office just now - it's close to 30! There are a lot of cars, street lights, utility meters etc in the world that aren't connected. In fact, in a separate Cisco announcement, 99% of the world's devices are NOT yet connected to the internet.

"Why do need to sprinkle sensors all over the planet"
Careful and planned deployment of sensors all over the planet has the potential to improve our lives and invigorate the economy. None of us can deny technological progress because it might be used for ill. You're from Jersey - apparently - not North Korea. Perhaps the good could outweigh the bad?

I think this is coming true every day. One trivial example, the tire pressure in my car's four tires is monitored remotely all of the time. Along with the function of a host of other components in the car.
Does anyone think this trend will reverse itself? Of course not. Does anyone think we have reached a plateau? Why?
Whether all of this ever-more-ubiquitous computing will generate $14T by 2020, in new hardware and services, is anyone's guess. My bet is, the number was thrown out there to get the requisite "ooohs" and "aaahs," and heads nodding.
No question that there would be absolutely no incentive to to moving along this path, as we have been at the very least since WWII, unless people could make money from it.

There has long been a vision of a future of ubiquitous computing in which ordinary processes are instrumented by ultra low cost low power networked nodes.
I believe some of this will come true eventually, but how much and when is very hard to say.
I suspect some of it may never pan out because the momentum of doing nothing or letting an analog/mechanical process stay in place is very great.

It is the pinnacle of hyping IoT, in my opinion.
I think the Cisco thesis is valid: IoT could in a best case scenario extend beyond today's IT budgets to existing and new line of business budgets creating an expansion market. But $14T is clearly a grand wish.

These are M2M connections of IoT devices that instrument processes like the factory floor, utility grids and crop irrigation and a bazilloion other things.
People won't own their IoT nodes like they own smartphones.

Again they aren't saying it costs $14T to buy 50B IoT nodes.
They are saying there is $14T in business value (productivity gains, new customer experiences, etc.) to be had in installing the 40-50B nodes.